The present invention generally relates to an electrical hearing aid device with a housing in which an integrated amplifier circuit is arranged having at least a microphone, switch and/or connection means, filter means, amplifier means and a voltage source. The amplifier circuit also has at least one earphone allocated to it. A protective device is provided and is fashioned against high-frequency electrical waves.
Parasitic electromagnetic radiation is demodulated in active components of an electronic hearing aid circuit. The low-frequency noise signal can then lead to the outage or, respectively, to a reduction in the functionability of an electrical hearing aid device.
For electromagnetic shielding of a hearing aid from radio signals of outside transmission devices, such as, for example, mobile radiotelephone devices, car telephones, microwave irradiation devices of other RF transmitters, German Patent No. DE-C-43 43 702 provides a shielding of the hearing aid housing such that the hearing aid housing is formed of at least two electrically conductive parts that can be electrically conductively connected via a high-frequency seal. Since the hearing aid housing also has openings for the admission and output of sound as well as clearances for switch means, potentiometers, controls, programming plugs or the like and a battery compartment to be opened or an accessible battery compartment, an electromagnetic housing shielding has various problem locations.
German Patent No. DE-C-43 43 703 discloses a hearing aid worn at the head that has a housing in which an amplifier circuit is arranged that has at least a microphone, an earphone and a battery wherein at least one protective device fashioned as an electrically conductive amplifier circuit from high-frequency electrical waves is provided such that the protective means for high-frequency has a conductive connection to an electrical terminal of the amplifier circuit and further wherein electrical means that form an electrical resistance for the high-frequency are provided in the conductive connection.
Modern hearing aid circuits are distinguished by LSI active circuits having only minimal outside wiring. All non-linear components are, therefore, usually located within the integrated circuit. Line-bound high-frequency noise currents can thus be demodulated only in the integrated circuit and, thus, lead to a degradation or, respectively, to the functional outage of the hearing aid.